Re: [PATCH 04/33] vfs: Export rw_verify_area() for use by cachefiles

From: Christoph Hellwig
Date: Tue Feb 16 2021 - 05:28:29 EST


On Mon, Feb 15, 2021 at 03:45:01PM +0000, David Howells wrote:
> Export rw_verify_area() for so that cachefiles can use it before issuing
> call_read_iter() and call_write_iter() to effect async DIO operations
> against the cache. This is analogous to aio_read() and aio_write().

I don't think this is the right thing to do. Instead of calling
into ->read_iter / ->write_iter directly this should be using helpers.

What prevents you from using vfs_iocb_iter_read and
vfs_iocb_iter_write which seem the right level of abstraction for this?